{"id":5409,"date":"2017-01-03T11:45:47","date_gmt":"2017-01-03T10:45:47","guid":{"rendered":"http:\/\/www.gemac-fieldbus.com\/?p=5409\/"},"modified":"2025-10-27T12:49:18","modified_gmt":"2025-10-27T11:49:18","slug":"suggested-bit-timing-and-bus-length","status":"publish","type":"post","link":"https:\/\/alt.gemac-fieldbus.com\/en\/suggested-bit-timing-and-bus-length\/","title":{"rendered":"Suggested bit timing and bus length"},"content":{"rendered":"<div id='av_section_1'  class='avia-section av-7ed8i9-ee21f70bd562fd14e75a0b39d2405a61 main_color avia-section-default avia-no-shadow  avia-builder-el-0  avia-builder-el-no-sibling  avia-bg-style-scroll container_wrap sidebar_right'  ><div class='container av-section-cont-open' ><main  role=\"main\" itemprop=\"mainContentOfPage\"  class='template-page content  av-content-small alpha units'><div class='post-entry post-entry-type-page post-entry-5409'><div class='entry-content-wrapper clearfix'>\n\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-5h9o1d-36591faf708133c02e662cb3c9799974\">\n.flex_column.av-5h9o1d-36591faf708133c02e662cb3c9799974{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div  class='flex_column av-5h9o1d-36591faf708133c02e662cb3c9799974 av_two_third  avia-builder-el-1  el_before_av_one_third  avia-builder-el-first  first flex_column_div av-zero-column-padding  '     ><section  class='av_textblock_section av-jj9t3c84-9c92a8fb30ebfdeebbcfb3d8a60c8438 '   itemscope=\"itemscope\" itemtype=\"https:\/\/schema.org\/BlogPosting\" itemprop=\"blogPost\" ><div class='avia_textblock'  itemprop=\"text\" ><h3 class=\"faq-title flush-left\">Suggested bit timing and bus length<\/h3>\n<div class=\"faded\"><\/div>\n<div class=\"thread-body bleed\">\n<p><strong>Bittiming as in CiA Draft Standard 102 Version 2.0<\/strong><\/p>\n<table>\n<thead>\n<tr>\n<td>Bit rate <em>(1)<\/em><\/td>\n<td>Bus length<\/td>\n<td>Nominal Bit time<\/td>\n<td>Number of<br \/>\ntime quanta per bit<\/td>\n<td>Location of sample<br \/>\npoint time quanta<\/td>\n<td>Location of sample point<br \/>\npercentage<\/td>\n<\/tr>\n<\/thead>\n<tbody>\n<tr>\n<td>10 kbit\/s<\/td>\n<td>5000 m <em>(3)<\/em><\/td>\n<td>100 \u00b5s<\/td>\n<td>16<\/td>\n<td>14<\/td>\n<td>87,5 %<\/td>\n<\/tr>\n<tr>\n<td>20 kbit\/s<\/td>\n<td>2500 m <em>(3)<\/em><\/td>\n<td>50 \u00b5s<\/td>\n<td>16<\/td>\n<td>14<\/td>\n<td>87,5 %<\/td>\n<\/tr>\n<tr>\n<td>50 kbit\/s<\/td>\n<td>1000 m <em>(3)<\/em><\/td>\n<td>20 \u00b5s<\/td>\n<td>16<\/td>\n<td>14<\/td>\n<td>87,5 %<\/td>\n<\/tr>\n<tr>\n<td>125 kbit\/s<\/td>\n<td>500 m<em> (2)<\/em><\/td>\n<td>8 \u00b5s<\/td>\n<td>16<\/td>\n<td>14<\/td>\n<td>87,5 %<\/td>\n<\/tr>\n<tr>\n<td>250 kbit\/s<\/td>\n<td>250 m <em>(2)<\/em><\/td>\n<td>4 \u00b5s<\/td>\n<td>16<\/td>\n<td>14<\/td>\n<td>87,5 %<\/td>\n<\/tr>\n<tr>\n<td>500 kbit\/s<\/td>\n<td>100 m<\/td>\n<td>2 \u00b5s<\/td>\n<td>16<\/td>\n<td>14<\/td>\n<td>87,5 %<\/td>\n<\/tr>\n<tr>\n<td>800 kbit\/s<\/td>\n<td>50 m<\/td>\n<td>1,25 \u00b5s<\/td>\n<td>10<\/td>\n<td>8<\/td>\n<td>80 %<\/td>\n<\/tr>\n<tr>\n<td>1 Mbit\/s<\/td>\n<td>25 m<\/td>\n<td>1 \u00b5s<\/td>\n<td>8<\/td>\n<td>6<\/td>\n<td>75 %<\/td>\n<\/tr>\n<\/tbody>\n<\/table>\n<p>Oscillator frequency: 16 MHz +\/-0.1% (1000 ppm)<br \/>\nSampling mode: Single sampling SAM = 0<br \/>\nSynchronization mode: Recessive to dominant edges only SYNC = 0<br \/>\nSynchronization jump width: 1 * tq SJW = 0<br \/>\nPhase Segment 2: 2 * tq TSEG2 = 1<\/p>\n<p><em>Note 1:<\/em> Rounded bus length estimation (worst case) on basis 5 ns\/m propagation delay and a total effective ECU-internal (Elec. Control Unit) in-out delay as follows:<\/p>\n<ul>\n<li>1M-800 kbit\/s: 210ns<\/li>\n<li>500 &#8211; 250 kbit\/s: 300 ns (includes 2 * 40 ns for optocouplers)<\/li>\n<li>124 kbit\/s: 450 ns (includes 2 * 100 ns for optocouplers)<\/li>\n<li>50 &#8211; 10 kbit\/s: 1.5 tq; Effective delay = delay recessive to dominant plus dominant to recessive divided by two.<\/li>\n<\/ul>\n<p><em>Note 2:<\/em> For bus length greater than about 200 m the use of optocouplers is recommended. If optocouplers are placed between CAN controller and transceiver this affects the maximum bus length depending upon the propagation delay of the optocouplers<br \/>\ni.e. -4m per 10 ns\u00a0propagation delay of employed optocoupler type.<\/p>\n<p><em>Note 3:<\/em> For bus length greater than about 1 km bridge or repeater devices may be needed.<\/p>\n<\/div>\n<\/div><\/section><\/div>\n<style type=\"text\/css\" data-created_by=\"avia_inline_auto\" id=\"style-css-av-fj3mp-44f5e356ae88fcdf03f9eb7571037a0d\">\n.flex_column.av-fj3mp-44f5e356ae88fcdf03f9eb7571037a0d{\nborder-radius:0px 0px 0px 0px;\npadding:0px 0px 0px 0px;\n}\n<\/style>\n<div  class='flex_column av-fj3mp-44f5e356ae88fcdf03f9eb7571037a0d av_one_third  avia-builder-el-3  el_after_av_two_third  avia-builder-el-last  flex_column_div av-zero-column-padding  '     ><div  class='avia-builder-widget-area clearfix  avia-builder-el-4  avia-builder-el-no-sibling '><div id=\"rpwe_widget-3\" class=\"widget clearfix rpwe_widget recent-posts-extended\"><style>.rpwe-block ul{\r\nlist-style: none !important;\r\nmargin-left: 0 !important;\r\npadding-left: 0 !important;\r\n}\r\n\r\n.rpwe-block li{\r\nborder-bottom: 1px solid #eee;\r\nmargin-bottom: 10px;\r\npadding-bottom: 10px;\r\nlist-style-type: none;\r\n}\r\n\r\n.rpwe-block a{\r\ndisplay: inline !important;\r\ntext-decoration: none;\r\n}\r\n\r\n.rpwe-block h3{\r\nbackground: none !important;\r\nclear: none;\r\nmargin-bottom: 0 !important;\r\nmargin-top: 0 !important;\r\nfont-weight: 400;\r\nfont-size: 16px !important;\r\nline-height: 1.5em;\r\n}\r\n\r\n.rpwe-thumb{\r\nborder: 1px solid #eee !important;\r\nbox-shadow: none !important;\r\nmargin: 2px 10px 2px 0;\r\npadding: 3px !important;\r\n}\r\n\r\n.rpwe-summary{\r\nfont-size: 12px;\r\n}\r\n\r\n.rpwe-time{\r\ncolor: #bbb;\r\nfont-size: 11px;\r\n}\r\n\r\n.rpwe-comment{\r\ncolor: #bbb;\r\nfont-size: 11px;\r\npadding-left: 5px;\r\n}\r\n\r\n.rpwe-alignleft{\r\ndisplay: inline;\r\nfloat: left;\r\n}\r\n\r\n.rpwe-alignright{\r\ndisplay: inline;\r\nfloat: right;\r\n}\r\n\r\n.rpwe-aligncenter{\r\ndisplay: block;\r\nmargin-left: auto;\r\nmargin-right: auto;\r\n}\r\n\r\n.rpwe-clearfix:before,\r\n.rpwe-clearfix:after{\r\ncontent: &quot;&quot;;\r\ndisplay: table !important;\r\n}\r\n\r\n.rpwe-clearfix:after{\r\nclear: both;\r\n}\r\n\r\n.rpwe-clearfix{\r\nzoom: 1;\r\n}\r\n<\/style><h3 class=\"widgettitle\"><a href=\"https:\/\/gemac-fieldbus.com\/en\/faq\/\" title=\"Back to FAQ overview\">Back to FAQ overview<\/a><\/h3><div  class=\"rpwe-block\"><hr>\r\n<h3>More in General<\/h3><ul class=\"rpwe-ul\"><li class=\"rpwe-li rpwe-clearfix\"><h3 class=\"rpwe-title\"><a href=\"https:\/\/alt.gemac-fieldbus.com\/en\/can-bus-wiring-test\/\" target=\"_self\">CAN bus wiring test<\/a><\/h3><\/li><li class=\"rpwe-li rpwe-clearfix\"><h3 class=\"rpwe-title\"><a href=\"https:\/\/alt.gemac-fieldbus.com\/en\/can-symboleditor-manual\/\" target=\"_self\">CAN Symboleditor Manual<\/a><\/h3><\/li><li class=\"rpwe-li rpwe-clearfix\"><h3 class=\"rpwe-title\"><a href=\"https:\/\/alt.gemac-fieldbus.com\/en\/canbusview-xl-iii-can-quick-tester-c-qt15-and-devicenet-analyzer\/\" target=\"_self\">CANBUSview XL III, CAN Quick Tester C-QT15 and DeviceNet Analyzer<\/a><\/h3><\/li><li class=\"rpwe-li rpwe-clearfix\"><h3 class=\"rpwe-title\"><a href=\"https:\/\/alt.gemac-fieldbus.com\/en\/cantouch-vs-can-bus-tester-2-the-decision\/\" target=\"_self\">CANtouch vs. CAN-Bus Tester 2, the decision<\/a><\/h3><\/li><li class=\"rpwe-li rpwe-clearfix\"><h3 class=\"rpwe-title\"><a href=\"https:\/\/alt.gemac-fieldbus.com\/en\/detection-of-short-circuits-in-the-can-bus-error-patterns\/\" target=\"_self\">Detection of short circuits in the CAN bus &#8211; 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